Dosimetric Specific Absorption Rate (SAR) measurements for, inter alia, mobile phone and radio base station antennas are widely used today.
In the standard procedure used today, a probe is used to scan a volume inside a “phantom”, i.e. a model intended to resemble the human body, usually a container filled with a body-tissue equivalent liquid.
The probe is used to register the amplitude of the vector components of the electric field emitted by the device which is to be measured. The antenna or device under test is placed on or near the surface of the phantom. The amplitude of the electric field vector components are measured, and the mass-averaged SAR values are determined, for example by means of a sliding spatial averaging.
Examples of existing solutions for SAR measurements are volumetric scan in the entire volume, sparse volumetric scan with data fitting to a given model, and area scan of SAR and propagation into a volume using attenuation factors from previous experiments.
The existing solutions provide good SAR measurements, but can be said to have drawbacks in that they are relatively time-consuming, and in some cases model dependent, i.e. tailored to a certain device or type of device.
Patent EP 1 615 041 discloses a device for measuring the SAR value of a cellular telephone, but the device of that document measures both the amplitude and the phase of an electric or magnetic field.
U.S. Pat. No. 5,789,929 discloses a method for SAR measurements which involves measuring two orthogonal magnetic fields, and does not appear to disclose anything regarding the use of measured amplitudes of the magnetic or the electric field in order to arrive at the complex electric field.